Because induction of chronic inflammation in the spinal cord by HTLV-1-infected T-cells was recognized as the major pathogenic mechanism underlying HAM/TSP, anti-inflammatory and antiviral therapies have been tested [10], and some clinical benefit has been demonstrated for corticosteroids, mainly oral prednisolone and intravenous methylprednisolone [11], interferon-α [12] and IFN-β1 [13]. Here, IFNB1 is linked to tropical spastic paraparesis.